The present application relates to a semiconductor structure and a method of forming the same. More particularly, the present application relates to a semiconductor structure including a strained silicon germanium alloy fin that can be employed as a channel material for a FinFET device and having improved overlay capacitance. The present application also provides a method for forming such a semiconductor structure.
For more than three decades, the continued miniaturization of metal oxide semiconductor field effect transistors (MOSFETs) has driven the worldwide semiconductor industry. Various showstoppers to continued scaling have been predicated for decades, but a history of innovation has sustained Moore's Law in spite of many challenges. However, there are growing signs today that metal oxide semiconductor transistors are beginning to reach their traditional scaling limits. Since it has become increasingly difficult to improve MOSFETs and therefore complementary metal oxide semiconductor (CMOS) performance through continued scaling, further methods for improving performance in addition to scaling have become critical.
The use of non-planar semiconductor devices such as, for example, semiconductor fin field effect transistors (FinFETs) is the next step in the evolution of complementary metal oxide semiconductor (CMOS) devices. Semiconductor fin field effect transistors (FETs) can achieve higher drive currents with increasingly smaller dimensions as compared to conventional planar FETs.
In order to extend FinFET devices beyond the current technology node, there is a need to boost the performance by using high mobility channel materials such as, for example, strained silicon germanium (SiGe). In current SiGe FinFETs, the SiGe fins suffer from strain relaxation do to cutting the SiGe fins to a desired length. In such instances, the strain relaxes, especially at the end portions of the SiGe fins. Short SiGe fins are even more prone to the effect of strain relaxation. There is thus a need for providing a structure and method to maintain strain in SiGe fins.